The invention generally concerns a rearview mirror, particularly for motor vehicles, having an integral display element and a picture taking device.
It is common knowledge to equip vehicles with so-called back-up aid facilities, which feature one or more sensors. The sensors may, for instance operate on an ultrasonic basis and be placed on the rear of the vehicle. Evaluation and display apparatuses, connected to said sensors, may be placed in the cockpit or the driver""s compartment. In particular, for large commercial vehicles, such trucks as semi-trailers, articulated vehicles, and the like, back-up aid facilities furnish great help for the driver. With such help in back-up maneuvering, a display can be made of the distance to an obstruction or to a target of the maneuvering, for instance, to a loading dock. The sensor(s) placed at the rear of a vehicle determine the distance to an obstruction or the said target and this distance is displayed on a monitor in the driver""s compartment. The distance can be shown either directly in meters and centimeters by means of a seven segment display, or the display will exhibit one or more of preferably different colored signal lamps (Light Emitting Diodes, hereinafter LEDs) by means of which the distance to an obstruction or the target of the maneuvering is shown in definite increments. Additionally, acoustic signals can be employed.
Where back-up maneuvering is concerned, the driver is, in great measure, dependent upon the information, which is seen in the outside rearview mirror. With the aid of the rearview mirrors, which are, as a rule, on both sides of the cab, the driver is in a position to maneuver safely. This depends, of course, on appropriate know-how and experience. In connection with a back-up aid of the described kind, very large vehicles with a non-visible rear area can maneuver with safety.
The disadvantage in the described situation is that during the maneuvering with the help of the two rearview mirrors and the back-up aid, the driver""s attention is being given continually to one of the two rearview mirrors, or between two rearview mirrors, and must then wander also to a display arranged on or in the instrument board. This stresses the concentration and also impairs the exactness of judgement regarding the images in the mirrors or in the back-up aid display. The latter is particularly significant if very highly contrasting brightness conditions exist between the image in the rearview mirrors and that of the back-up aid display, since the eye always requires a certain elapsed time to adapt to a bright-dark, dark-bright change in the viewing field. Further, the image in the rearview mirror(s) and the display, as a rule, lie at different distances, so that the eye in the continual change of view requires also a certain accommodation time for this. All these factors add up to the point that upon back-up maneuvering with the help of the rear view mirrors and the display of a back-up aid a great deal of know-how and concentration are expected from the driver during the operation.
As introduced above, the drivers of trucks or other vehicles have available very little, if any, field of sight to the rear. These drivers, when backing or maneuvering, are especially dependent upon one or the other of the external rearview mirrors in order to maneuver safely. In practice, often a single mirror with a single mirror pane or glass does not suffice, even when there is respectively one mirror to the left and another to the right, that is to say, one mirror placed on the driver""s side and one on the passenger""s side. A single mirror is, in most cases, not in a position to reflect to the driver all the important zones to the sides and rear of the vehicle. Thus it has become known, to place on the sides of the vehicle a plurality of mirrors with differently adjusted angles to enable the driver to have the great possible panoramic field of view. An installation of such a plurality of rearview mirrors is, however, costly, deteriorates the streamlining of the vehicle, and thus increases the consumption of fuel. In the case of certain vehicles, particularly busses, this is also not desirable from the standpoint of design. Further, with an increasing number of mirrors, the number of mirror surfaces likewise increases. This naturally increases the possibilities of breakage.
In the case of a change of drivers, then the position of the majority of the mirrors must also be set anew, which is time consuming and likewise impractical. In addition, all mirror surfaces must be regularly cleaned and provided with heating apparatuses, in order to assure a continuous line of sight to the rear.
The invention creates a rearview mirror, which enables the driver of a vehicle to accept along with the information communicated to him by the rearview mirrors additional information without having to take his eyes off the rearview mirrors.
To achieve the above purpose, the present invention proposes a rearview mirror, particularly for motorized vehicles, with a mirror pane, wherein in the top view direction, behind the mirror pane, is placed at least one radiation emitting, display element, which radiates through the mirror pane.
Within the scope of the present invention, there would be one radiation emitting display element located behind the mirror pane, whereby this display element would emit its radiation through the mirror pane.
Mirror panes, for instance such as Chrome-glass, to a certain degree are transparent for such radiation as enters through the back side of the mirror pane.
At the same time, the mirror panes remain reflective and mirror-like, when seen from the front side. The present invention makes use of this, since it places at least one radiation emitting display element behind the mirror pane. This display, associated with this element, for an observer in front of the mirror, lies, more or less in the mirror pane plane and the information transmitted by the display element appears through the mirror pane xe2x80x9cinxe2x80x9d the usual reflected image, which is reflected from the mirror pane.
In this way, it is possible to place the emitting display element(s) of back-up aid facilities, in accord with the teachings of the present invention, behind the mirror pane. When this is done, these display elements merge their corresponding information through the mirror pane, blending into the reflective image on the mirror pane. The observer then receives thus, at one glance, information from the mirror image on the mirror pane, as well as information from the display element(s). The view of the driver need no longer be divided between the mirror and a separate display apparatus. The driver""s view need not wander back and forth to the instrument panel, but his attention remains, during the back-up maneuver, solely on the mirror. This is the result of all the collected data for the back-up operation being presented at one glance. More precise and fatigue-free driving becomes possible by these measures.
The display element can radiate in the spectrum of either visible or infrared light. In practice, the emission of light in the visible spectrum is used in the majority of cases, since with such light a direct optical display is possible. For certain applications, an emission of infrared can be of interest, for instance, for information which is not visible to the naked eye, or for coding between the vehicle and a stationary point for supervision and registration. In this regard, it should be mentioned that the object of the present invention is directed toward bringing radiation emitting display elements in general behind the mirror pane.
A direct visual information transmission to the driver by means of these display elements is only a possible and an especially advantageous application of the concept of the invention. In accord with a further embodiment, a plurality of light radiating display elements may advantageously be assembled in groups behind the mirror pane. In this case it becomes possible to transmit even more complex data for instance a decreasing spatial interval between the tail gate of the vehicle and an obstruction or target of maneuvering while backing up. Alternatively, for instance, a longer series of display elements may be utilized set next to each other, among which one or the another is either active or inactive, if the tail gate of the vehicle nears an obstruction or the target of back-up maneuvering. The method of function in this case is that as the approach comes to a minimal distance, either all display elements deactivate or cause a display light-up in the form of a figurative barrier. A further possibility in the presentation of information would be enabling a blinking display, the frequency of which is directly proportional to the distance to the obstruction or the target of the backing-up maneuvering.
Preferably, LEDs serve as display elements, in particular high capacity LEDs. Preference is given because of small size, modest power demands, high life expectancy, freedom from sensitivity to vibration and impact, and availability in various dimensions and shapes. A further advantage is also obtained, when, in accord with a further embodiment, the LEDs are of varied colors. By this means, the data content, which can be transferred through the mirror pane, can still be amplified.
Instead of, or in addition to LEDs, the display elements can activate one or more xe2x80x9cseven segmentxe2x80x9d displays. In this case, it is possible to display the intervening distance from the tail gate of the vehicle to the obstacle or target of the back-up maneuvering, in direct analog form, i.e. in meters or centimeters. Also other data such as the outside temperature, the assured clear distance to the preceding vehicle on the road, a switching on of the mirror heating, a memory function for the mirror adjustment motor, turn signal blinkers, or the presence of persons in the non-visible dead zone can be captured and subsequently converted into display.
Based on the fact that display elements are arranged behind the mirror pane and must radiate through the mirror pane, there arises the advantage, on the one hand, that the display image evolved from display element emission appears practically directly on the already reflecting surface of the mirror. Furthermore, the enclosed display elements are protected from weather and environmental hazards. However, there arises due to the radiation through the mirror pane a certain weakening of the displayed image which is observed by the driver. In unfavorable light situations, this can lead to a situation wherein the visual light projected into the mirror pane of the rearview mirror cannot be read or deciphered or is only poorly recognizable.
On this account, in accord with another embodiment of the present invention, the reflective coating of the surface area immediately in front of the display elements is at least partially removed. This permits the emanated display to proceed from the display element to the visualizing surface with the least hindrance through the transparent or translucent material of the mirror pane. Thus the display is not weakened. In order to prevent that by this partial removal of the reflective coating the rearview mirror, that is, its reflective layer, appears to be xe2x80x9cperforatedxe2x80x9d, in accord with yet another advantageous embodiment of the present invention, the removing of the reflective layer is carried out in the form of thin, incised lines, parallel to one another or in the form of small, individual dots. Again, filling a surface shape sized to conform to the emitting aperture of the display element, the above removing means are applied to the mirror front surface.
In particular, when the removed surface of the mirror is in the form of thin, incised lines, parallel to one another or in the form of small, individual dots, this removing of the mirror coating is essentially no longer visible from a certain observational distance, and essentially does not impair the presentation of the mirror image. A further possibility is to so abrade the reflective layer with distinctive symbols or so-called pictograms which illuminate when one or another of the several display elements behind the reflective layer are activated.
In order to prevent possible divergent radiation, or halo formations about the true point of light, or images, the back side of the mirror with the exception of the transparent areas for visible light or radiation can be covered with, for instance, a lacquer coating.
The partial removing or abrasion of the reflective layer can, for instance, be carried out by a precision laser, by an etching procedure, by sand blast abrasion, by incision of lines, or by a masking done when the reflective mirror coating was applied.
The direction of radiation of the display elements can be at an angle either away or toward the observer, so that the resulting image in various directions appears differently intense or bright, and also clear or less clear, i.e., to the point of not being seen at all. The radiation direction of the display elements can be directed through lenses, which are ground into the material of the mirror pane or are fastened thereto.
The present invention also provides in another aspect, a rearview mirror having a mirror pane, in particular a rearview mirror for motorized vehicles, wherein the rearview mirror is characterized, in that behind the mirror pane, an apparatus for taking pictures is placed.
By the term xe2x80x9capparatus for taking picturesxe2x80x9d it is to be understood, for the present invention and in the widest scope, an element which receives incoming radiation within a definite wave spectrum, or else an apparatus responsive to such radiation. Further, the incoming radiation must be convertable into a displayed and visible picture by the element or apparatus.
In a concrete embodiment example and in accord with a preferred embodiment form of the present invention, the picture taking apparatus is a camera. By this means, it is possible to display a picture taken by the camera on a monitor or on the instrument panel of the vehicle. Since, in this matter, the picture taking apparatus, i.e. the camera, can have a direction of view differing from that of the plane of the mirror, then the camera has the ability to display a picture from a different area than that of the mirror. The driver of the vehicle sees in the mirror surface of the rearview mirror a partial view of the zone lying behind or to the side of the vehicle and sees in the monitor another zone lying behind or to the side of the vehicle. The latter will be as the view is caught by the picture taking apparatus. The rearview mirror of the present invention thus unifies, more or less, two rearview mirrors into one, without the requirement that the size of the mirror surface and/or the number of the mirror surfaces be increased.
The direction of the view of the picture taking apparatus can be entirely different from that of the surface of the plane of the mirror glass. Thus, for instance, the picture taking apparatus can be directed downward at a right angle to the pane of the mirror, in order to enable the driver of the vehicle to supervise the area before and behind the front axle. The remaining areas, to the side or behind the vehicle will be observed as seen in the mirror surface.
In accord with a further advantageous embodiment, the picture taking apparatus, however, can also xe2x80x9cseexe2x80x9d through the mirror pane. It is known, that mirror panes of mirrors, have less than one-hundred percent reflecting powers, but show also a certain translucence. This translucence can be sufficient to allow a response from the picture taking apparatus set behind the mirror pane.
Advantageously, however, the reflective mirror layer of the mirror pane is at least partially removed in an area in front of the picture taking apparatus in order to achieve a locally improved transparency of the mirror pane. This partial removal of the mirror layer can, for instance, be made in the form of fine lines, essentially parallel to one another, or in the form of single dots. If a mirror layer of this kind is partially removed, then the rearview abilities of the rearview mirror is only immaterially reduced. However, a substantially greater translucency of the mirror pane is achieved. The partial removal of the mirror layer can, for instance, be made by means of a laser, or by etching or through a fine line scoring process, or yet even by corresponding masking when the reflective mirror layer was applied.
The picture taking apparatus is preferably in the form of a camera, and more preferably a CCD camera, which can have sensitivities either in the area of visible light, or in the area of infrared light. If, in these cases, the camera is augmented by at least one radiation emitting element of a corresponding wave length, then, in the case of bad visibility, (at night, in fog or heavy rain, etc.) improved visibility is achieved by the picture taking apparatus or camera. Particularly, when the picture taking apparatus is sensitive to infrared light, use of a lamp emitting in the infrared spectrum, can provide a sufficiently clear and well illuminated field of vision without degradation of the surroundings, that is, for instance, without glare. The same advantageous effect may be obtained also with one or more light emitting diodes (LED) as radiation element(s).
It will prove advantageous, if the radiation emitting element, of which there is at least one, is at least automatically and simultaneously activated as the camera is switched on.
The direction of viewing of the picture taking apparatus is best changeable and in this vehicle case especially advantageous if it is changed by remote control. In doing this, it is possible, for instance, to change the direction of view from the driver""s seat by a control lever, or joystick. The desired or required viewing direction can be quickly adjusted this way and, moreover, quickly modified upon change of drivers.
As already mentioned, the picture taking apparatus is connected to a picture evaluation means and to a display module, in order to make the picture gained from the picture taking apparatus visible on a monitor or on the instrument board.
It should be understood, that the object of the present invention applies in like manner, to a rearview mirror, which contains two or more picture taking apparatuses or cameras. Further that these picture taking apparatuses or cameras may possess respectively different directions of view or may be, as is preferred, governed by remote control to obtain changeable directions of view.